1. Field of the Invention
The present invention relates to a process for the production of strips of fried potato, and more particularly to that comprising the steps of cutting raw peeled potatoes into rectangular strips of the same size, blanching the strips, par-frying and immediately freezing the par-fried strips, and then finish frying frozen strips in an edible oil, while subjecting them to microwave energy.
2. Related Arts
As well known products, wherein raw potatoes are washed, peeled, cut into a predetermined shape and deep fat fried in an edible oil, there are so-called potato chips, french-fried potatoes and the like.
Among them, the potato chips have been manufactured by frying the cut potato pieces in the edible oil at a temperature of from 130.degree. to 180.degree. C. and are characterized in having a crisp mouth feel and a low moisture content of from 0.1 to 5% by weight, which allows marketing of the product without a need for refrigeration. On the other hand, the french-fried potatoes have been manufactured by cutting the raw potatoes into rectangular strips, for instance, strips with 10.times.10 millimeters in cross-section, washing in cold water, blanching and then frying the strips in edible oil at a temperature of about 180.degree. C.
U.S. Pat. No. 4,109,020, British Pat. Nos. 1034035 and 1344125 as well as Japanese Pat. No. 55-29917 (A) teach utilization of microwave to heat pieces of potatoes, after having fried the same.
It has been considered that the french-fried potatoes, to which the present invention, pertains are difficult for marketing, since the outer layer thererof is in a dried state to give a crisp mouth feel but the core portion thereof still has a higher moisture content, which allows them to gradually lose a crisp mouth feel, whereby their flavor and taste are remarkably reduced, as they get cold.
In the market, there has been sold a frozen product of french-fried potatoes, which has been prepared by cutting raw potatoes into rectangular strips with cross-section of 10.times.10 millimeters, frying the strips, and then freezing the same. If the frozen strips are fried in an edible oil for a long period of time to dehydrate them to such an extent that they are able to be marketed without a need for refrigeration, however, wrinkles generate in the outer layer thereof to provide fried strips in a curved state, which are not welcomed by consumers. Further, an extension of frying time does not provide an adequate dehydration, if fried in an oil at too low temperature, for instance at about 100.degree. C., and if fried in an oil at a relatively high temperature, for instance at about 140.degree. C., a scorching will occur on the outer layer of the strips before completing dehydration from the core portion thereof, so that the resulting fried potato strips become one without market value.
According to experiments made by the inventors, it has been found that relatively thin potato strips formed by cutting whole potatoes, preferably peeled into rectangular strips with 2.times.2 millimeters cross-section, may be made into fried potato strips having a desired crisp mouth feel and a low moisture content to allow their marketing without a need for refrigeration, under the frying conditions similar to those for said potato chips, and that it is impossible under such frying conditions for potato chips to prepare french-fried potatoes having a rectangular shape with a cross-section of 3.times.3 millimeters or more, the desired mouth feel and a relatively low moisture content. It is the purpose of the present invention to produce such a product.
Each of said patents [U.S. Pat. No. 4,109,020, British Pat. Nos. 1034035 and 1344125 as well as Japanese Pat. No. 55-29917 (A)] suggests that potato strips can be dehydrated deep to its core portion, by frying raw potato strips in an edible oil and then subjecting the resulting fried potato strips to microwave energy. The inventors, therefore, have made an experiment, in accordance with such a method as taught therein. Namely, relatively thick strips of raw potato were fried at 180.degree. C. for 5 minutes until an outer layer thereof is turned to a light brown color, although the core portion has a relatively high moisture content, and then the resulting fried strips were transferred into a microwave oven for treating the strips to obtain strips dehydrated deep to its core portion, by subjecting to microwave energy for 5 minutes. However, the resulting potato strips shrinked and deformed in cross-section thereof, as shown in FIG. 1C, each strip was remarkably colored in dark brown at an intermediate portion thereof, in comparison with that in opposite ends and became curved or twisted. These matters will not permit the product to be sold in market.